The present invention relates to three-dimensional fly-through displays. In particular, ultrasound data is used for rendering a three-dimensional fly-through of a volume.
One fly-through technique for rendering provides virtual endoscopy. The user may better appreciate the internal structure of vessels or better identify areas of stenosis. Color power Doppler ultrasound data has been used with manual tracing for virtual endoscopy. However, color Doppler data has poor spatial resolution, so little detail about the texture of the structure is provided. Furthermore, the lighting model used is typically chosen arbitrarily. As a result, the displayed structural representation shows the geometry but provides poor textural representation. For example, some plaque may not be visible or represented in the images.
In U.S. Pat. No. 6,443,894, ultrasound data is used for generating a fly-though. Color Doppler information is used to identify a boundary. Texture information is then rendered from B-mode data by texture mapping or using the boundary to define B-mode data for volume rendering. As the user's perspective changes within a vessel, a new image is generated. A sequence of images is provided to simulate moving through a vessel detected using the Doppler information.
To avoid spatial inaccuracies provided with Doppler data, a boundary or surfaces are manually traced by users. Volume rendering is then provided based on the manually determined boundaries. Manual tracing may be time consuming.
Higher resolution computed tomography and magnetic resonance imaging provide for virtual endoscopy. A threshold is selected to create a cavity or identify a boundary in the high spatial resolution CT or MR data. The user's perspective or position is placed within the cavity or at a desired location relative to the boundary. A series of representations are rendered corresponding to navigating through or around the boundary or cavity with collision detection.
Three-dimensional and four-dimensional imaging (e.g., three-dimensional imaging as a function of time) may be useful for medical diagnosis, such as in cardiac and obstetric diagnosis. For ultrasound imaging, ever decreasing acquisition times may accelerate expansion of three- or four-dimensional usage in the above-described fields or other fields, such as vascular diagnosis. Increased image quality and spatial resolution are possible with ultrasound, such as provided in U.S. Pat. No. 6,679,843 (Publication No. 20030236460).